1. Field
One or more aspects of embodiments of the present invention relate to an electrolytic solution for a lithium battery and a lithium battery including the electrolytic solution.
2. Description of the Related Art
Lithium batteries are typically used as power sources for portable electronic devices such as camcorders, mobile phones, and laptop computers. Lithium secondary batteries are rechargeable at high rates and have energy density per unit of weight of about three times higher than that of lead storage batteries, nickel-cadmium (Ni—Cd) batteries, nickel-hydrogen batteries, and/or nickel-zinc batteries in related art.
A lithium battery operating at a high driving voltage is incompatible with an aqueous electrolytic solution that is highly reactive with lithium. For this reason, lithium batteries typically use an organic electrolytic solution. The organic electrolytic solution may be prepared by dissolving a lithium salt in an organic solvent. A suitable organic solvent may be stable at high voltages, may have a high ionic conductivity, a high dielectric constant, and a low viscosity.
For example, using a carbonate-based polar, non-aqueous solvent in a lithium battery may cause a side reaction between a negative electrode and/or a positive electrode and the electrolytic solution during initial charging, and consequentially may lead to an irreversible reaction using excess charges.
The irreversible reaction may result in a passivation layer (such as a solid electrolyte interface (SEI) layer) being formed on a surface of the negative electrode. The SEI layer may prevent or substantially reduce decomposition of the electrolyte and may also serve as an ion channel. The higher the stability of the SEI layer and the lower its resistance, the better the lifespan characteristics of the resulting lithium battery.
The irreversible reaction may also form a protection layer on a surface of the positive electrode. The protection layer may prevent or substantially reduce decomposition of the electrolytic solution during charging and discharging and may serve as an ion tunnel. The higher the stability of the protection layer at high temperature, the better the lifespan characteristics of the resulting lithium battery.
Therefore, there is a demand for an organic electrolytic solution capable of forming a stable SEI layer and/or protection layer, which may improve lifespan characteristics of a lithium battery.